Two residents of a burning North Side apartment building broke down a door and dragged a critically burned man to safety.

Nick Salazar said he smelled smoke, then heard fire alarms, then banging on his door. The man who did the banging then led him to another first-floor unit, where together they broke down the door and pulled the 45-year-old man who lived there to safety.

"I grabbed him by the wrist and felt something wet," Salazar said. "It was his skin."

The victim, who residents said they believed was a CTA bus driver, suffered burns to 75 percent of his body in the fire about 2:50 a.m. at the 4-story Ravenswood neighborhood residential building on the 4700 block of North Virginia Avenue, fire officials said.

Battalion Chief Thomas Lally said when firefighters arrived they found the burn victim in the building's lobby, about 20 feet from the first-floor apartment where the fire presumably broke out.

He was taken to Swedish Covenant Hospital in serious-to-critical condition before being transferred to Loyola University Medical Center in Maywood, officials said. The Loyola facility houses a burn unit.

One or two other residents were treated on the scene for minor breathing problems, Lally said.

The fire was brought under control by 3:11 a.m. Authorities couldn't immediately provide any additional details on the fire.

It was unclear how many, if any, of the residents were displaced. The American Red Cross of Greater Chicago said it was sending workers to offer assistance.

William Lee is a Tribune reporter. Randi Belisomo is a WGN-TV reporter